The cytochrome P450 gene superfamily in Drosophila melanogaster: Annotation, intron-exon organization and phylogeny

The cytochrome P450 gene superfamily is represented by 90 sequences in the Drosophila melanogaster genome. Of these 90 P450 sequences, 83 code for app arently functional genes whereas seven are apparent pseudogenes. More than half of the genes belong to only two families, CYP4 and CYP6. The CYP6 fami ly is insect specific whereas the CYP3 family includes sequences from verte brates. There are eight genes coding for mitochondrial P450s as deduced fro m their homology to CYP12A1 from the house fly. The genetic map of the dist ribution of D. melanogaster P450 genes shows (a) the absence of P450 genes on the chromosome 4 and Y, (b) more than half of the P450 genes are found o n chromosome 2, and (c) the largest cluster contains nine genes. Sequence a lignments were used to draw phylogenetic trees and to analyze the intron-ex on organization of each functional P450 gene. Only five P450 genes are intr onless. We found 57 unique intron positions, of which 23 were phase zero, 1 9 were phase one and 15 were phase two. There was a relatively good correla tion between intron conservation and phylogenetic relationship between memb ers of the P450 subfamilies. Although the function of many P450 proteins fr om vertebrates, fungi, plants and bacteria is known, only a single P450 fro m D. melanogaster, CYP6A2, has been functionally characterized. Gene organi zation appears to be a useful tool in the study of the regulation, the phys iological role and the function of these P450s. (C) 2001 Elsevier Science B .V. All rights reserved.